Oily coffee beans result from lipids within the bean coming to the surface in the form of oil. This can happen during a long roast, or more gradually as beans are stored after roasting. A coat of oil on beans doesn’t necessarily indicate they are poor quality or too old, but it does suggest a few factors to investigate.
Why are some coffee beans oily and some dry?
My “dry” coffee beans are a sign of freshness and craft roasting. An oily coffee bean is an indicator that your beans are either pretty old or were over-roasted (generally both). Industrial roasters typically roast to get an even color, not to procure excellent flavors.
It’s actually very normal for fresh, dark-roasted coffee beans to have an oily sheen. This is because dark beans are already full of oils, and the roasting process brings these oils to the surface. Some people think that oily coffee beans have more flavor, while others always prefer a drier roast.
How do you keep coffee beans from getting oily?
The best way to prevent oily coffee beans is to buy a light roast or medium roast coffee. If you do notice an oily surface then these beans have been left out too long before being packaged. You’ll end up with a bland or stale tasting coffee.
Do oily coffee beans have more flavor?
Some people think that oily coffee beans have more flavor, while others always prefer a drier roast. Changing the heat used and the roasting time will change how much oil is present on the beans; these differences in the roasting process are part of a roaster’s signature taste.
Why does coffee have an oily sheen?
In the coffee cherry, the oils are closer to the solid state. When you roast the cherries and they turn into coffee beans, a lot of changes take place. The CO2 that forms inside the coffee bean may seep out if you roast the bean for too long, and as it seeps out, it reacts with oxygen to produce that oily sheen.
If a medium- or light-roasted coffee has oil on the surface, it’s probably been there a long time and will taste flat and stale. On the other hand, a very dark French or Italian roast could look oily right away. Expect the roast flavours to dominate the flavour profile of these beans, with savoury flavours of smoke or even charcoal.
Dark roast coffee that is oily is often synonymous with bolder coffee brews. This is a common belief among many coffee drinkers. This also explains why espresso drinkers will lean towards the dark roast coffee. But the trick with any coffee brew is playing with the water to bean ratio and optimizing the coffee grind.
Why do beans get a coat of oil on them?
This can happen during a long roast, or more gradually as beans are stored after roasting. A coat of oil on beans doesn’t necessarily indicate they are poor quality or too old, but it does suggest a few factors to investigate.